JP3409352B2 - Method for producing aromatic compound - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic hydrocarbon compound mainly comprising paraffins having 6 or more carbon atoms.
The present invention relates to a method for producing aromatic compounds such as benzene and toluene useful in the petrochemical industry. [0002] Aromatic compounds such as benzene and toluene are produced by distillative separation of cracked gasoline when producing olefins by cracking naphtha.
Furthermore, it is also produced by reforming naphtha, which is mainly composed of paraffins having 6 to 8 carbon atoms during oil refining. [0003] In the reforming of naphtha, a platinum catalyst supported on alumina is mainly used. This catalyst can easily convert a hydrocarbon having 7 or more carbon atoms into an aromatic compound, but has a problem that the activity of aromatization is insufficient for a carbon number of 6, especially hexane. [0004] For this reason, a catalyst for aromatizing hexane has been studied. For example, US Pat. No. 4,104,320
At least 90% of the ion-exchangeable cations
The above are the alkali cations composed of potassium, rubidium and cesium, and L which supports platinum.
A method using a zeolite of the type as a catalyst is disclosed. In this method, the amount of the ion-exchangeable alkali cation is equal to or less than the amount of aluminum constituting the framework of the zeolite. JP-A-58-133835 discloses the use of a catalyst in which platinum is supported on an L-type zeolite ion-exchanged with barium as an alkaline earth metal. Further, Japanese Patent Application Laid-Open No. 61-138538 discloses a special method for supporting platinum on an L-type zeolite in which the ion-exchangeable cation is potassium. That is, in carrying platinum by ion exchange,
Ion exchange is performed in a solution in which both the platinum complex and potassium chloride are dissolved, excess solution is removed, and before drying substantially all of the solvent, platinum is deposited on the catalyst by an aging method. A method of uniformly loading is shown. In this method, the amount of the alkali cation is larger than the amount of aluminum constituting the framework of the zeolite, and the molar ratio of potassium chloride and platinum carried is, according to the examples, about 1.25 or less. Value. Further, it is stated that if a large amount of potassium chloride is present in the pores of the zeolite, it becomes difficult for the reaction raw material to reach platinum, and the activity is impaired. According to the prior art, benzene is obtained from hexane as a raw material at a yield of about 60%. However, since there are many decomposition products of hexane, a higher fragrance is obtained. There has been a demand for the yield of group compounds. In view of the above situation, as a result of intensive studies on a catalyst for producing an aromatic compound by reforming naphtha, surprisingly, by controlling the catalyst preparation method, The present inventors have found that an aromatic compound can be obtained in a high yield, and have completed the present invention. That is, in the present invention, in converting a hydrocarbon compound having 6 or more carbon atoms into an aromatic compound, the L-type zeolite is ion-exchanged with a Group VIII noble metal, and then a molar ratio of 2 to 10 with respect to the supported amount of the Group VIII noble metal. times of the alkali metal salts carrying, characterized by using obtained by firing at 100 ° C. to 600 ° C., the L-type zeolite was supported group VIII noble metal and an alkali metal salt as a catalyst and thereafter, aromatic This is a method for producing a compound. Hereinafter, the present invention will be described in more detail. In the method of the present invention, a catalyst supported on L-type zeolite is used. L-type zeolite is a kind of synthetic zeolite and is a crystalline aluminosilicate composed of SiO ₄ tetrahedron and AlO ₄ tetrahedron. Zeolite L has the general formula _{M 2 / n O · Al 2} O 3 · xSiO 2 · yH 2 O
(Where M is an ion-exchangeable cation, n is its valence, x is a number from 4 to 7 representing the Si / Al ₂ ratio,
Also, y is the amount of water of crystallization, which is 0 in the case of normal baking treatment). In a pure crystal, for example, when M is an alkali cation, the same number of moles as aluminum exists, and when M is an alkaline earth cation, half the number of moles of aluminum exists due to charge neutralization in the zeolite framework. . [0010] The method for preparing the L-type zeolite used in the method of the present invention is not particularly limited, and a product prepared by a known method can be used. Preferably, it is an L-type zeolite wherein M is an alkali cation, more preferably M is a potassium cation. In the method of the present invention, an L-type zeolite supporting a Group VIII noble metal and an alkali metal salt is used as a catalyst. The Group VIII noble metal is supported by an ion exchange method. The ion exchange method itself is not particularly limited as long as it is supported by the ion exchange method, and may be performed by a known method. For example, L-type zeolite can be added to an aqueous solution of a noble metal ammine complex or the like, kept at a predetermined temperature for a predetermined time, and then washed with water to remove excess complex, to obtain an L-type zeolite supporting a Group VIII noble metal. Examples of Group VIII noble metals include Ru, Rh, Pd, Os, Ir, and Pt, with Pt being preferred. In the method of the present invention, the alkali metal salt may be a halide of an alkali metal, a nitrate,
Sulfates and the like can be used, and among them, preferred are halides, more preferred are potassium halides, and particularly preferred is potassium chloride. This alkali metal salt is carried by the impregnation method without carrying out a treatment for decomposing the noble metal compound after carrying the group VIII noble metal on the L-type zeolite by ion exchange. The method of impregnation is not particularly limited, and the impregnation may be performed by a usual impregnation method. The catalyst used in the method of the present invention is obtained by impregnating and supporting an alkali metal salt and then calcining. In this case, since the calcination temperature affects the performance of the catalyst, the calcination temperature is 100 ° C to 600 ° C, preferably 120 ° C to 550 ° C, more preferably 200 ° C to 200 ° C.
400 ° C. Further, in the method of the present invention, after firing, the Group VIII noble metal is reduced and used in the gas phase using a reducing agent such as hydrogen or in the liquid phase using a reducing agent such as hydrazine. This reduction does not necessarily have to be performed during the preparation of the catalyst, and may be performed before the reaction in the reactor for producing the aromatic compound. Since the reduction temperature varies depending on the type of the reducing agent, it cannot be unconditionally determined,
In the case of a gaseous phase, it may be carried out at a temperature up to 600 ° C., and in the case of a liquid phase, it may be carried out at a temperature not lower than room temperature. The loading ratio of the supported Group VIII noble metal is 0.1 to 2.% based on the total weight of the catalyst, that is, the total of the L-type zeolite, the Group VIII noble metal and the alkali metal salt.
5%, preferably 0.2% to 2%. If the loading is less than 0.1%, the activity for producing an aromatic compound may not be sufficient. On the other hand, if it exceeds 2.5%, the activity is little improved, and it is not economical. The supported amount of the alkali metal salt is 1.5 or more, preferably 2 to 10 in molar ratio to the supported amount of the Group VIII noble metal. If the number of moles of the alkali metal salt relative to the number of moles of the group VIII noble metal is less than 1.5, the effect of supporting is not sufficient, and if it exceeds 10, the activity per catalyst weight tends to decrease. In the method of the present invention, a hydrocarbon compound having 6 or more carbon atoms is used as a raw material. The hydrocarbon compound having 6 or more carbon atoms may contain a lower hydrocarbon having less than 6 carbon atoms such as methane and ethane, a naphthenic compound, and an aromatic compound. A typical raw material is naphtha in petroleum refining. The reaction method is not particularly limited, and the reaction can be carried out in a fixed bed, a fluidized bed, or a moving bed. Also,
The reaction may be in a gas phase or a liquid phase. [0019] The reaction temperature is from 300 ° C to 600 ° C, preferably from 400 ° C to 550 ° C. The reaction pressure is from normal pressure to 50 atm, preferably from 2 to 45 atm. The feed rate of the raw material to the catalyst is represented by a liquid feed rate per unit catalyst weight (WHSV).
It is ^{1 to} 10 h ^-1 , preferably 0.5 to 5 h ^-1 . Further, the flow rate of hydrogen is represented by the molar ratio of hydrogen to the raw material, and is 1 to 50, preferably 1 to 20 in molar ratio. When the above reaction conditions are not satisfied, the activity may be insufficient or the selectivity may be reduced. EXAMPLES The present invention will be described below with reference to examples.
It goes without saying that the present invention is not limited to only these examples. In the examples, the catalyst is an alkali metal salt (moles of alkali metal salt with respect to the number of moles of noble metal of group VIII) / support amount of noble metal of group VIII-type of metal of group VIII / zeolite, and KL is potassium-type L-type zeolite. (Firing temperature). Example 1 Potassium type L-type zeolite (TSZ manufactured by Tosoh Corporation: TSZ)
-500) was added to an aqueous solution of tetraammineplatinum dichloride, followed by ion exchange. After being sufficiently washed and dried, it was added to an aqueous potassium chloride solution and dried. 300 ° C under air flow
Then, reduction was performed at 470 ° C. under a hydrogen stream to obtain a KCl (2) /0.5% Pt / KL (300) catalyst. This catalyst was charged into a fixed bed flow reactor, and an aromatization reaction of hexane was performed at a reaction temperature of 470 ° C., a hydrogen pressure of 5 atm, a hydrogen / hexane molar ratio of 6.0, and a WHSV of 2.4 h ⁻¹ . Table 1 shows the results. Examples 2 and 3 The firing temperature in an air stream was 120 ° C. and 550, respectively.
KCl in the same manner as in Example 1 except that
(2) /0.5% Pt / KL (120), KCl
(2) /0.5% Pt / KL (550) catalyst was obtained.
The reaction was carried out in exactly the same manner as in Example 1 except that the obtained catalysts were used. Table 1 shows the results. Example 4 KCl was prepared in exactly the same manner as in Example 1 except that the amount of potassium chloride was changed so that the molar ratio of potassium chloride to platinum was 4.
A (4) /0.5% Pt / KL (300) catalyst was prepared and reacted. Table 1 shows the results. Examples 5 and 6 The firing temperature was set to 120 ° C. and 550, respectively, in an air stream.
KCl in the same manner as in Example 4 except that
(4) /0.5% Pt / KL (120), KCl
(4) /0.5% Pt / KL (550) catalyst was obtained.
The reaction was carried out in exactly the same manner as in Example 4 except that the obtained catalysts were used. Table 1 shows the results. Example 7 KCl was prepared in exactly the same manner as in Example 1 except that the amount of potassium chloride was changed so that the molar ratio of potassium chloride to platinum was 6.
A (6) /0.5% Pt / KL (300) catalyst was prepared and reacted. Table 1 shows the results. Example 8 Using the catalyst obtained in Example 4, a reaction was carried out in exactly the same manner as in Example 1 except that the hydrogen pressure was changed to 3 atm. Table 1 shows the results. Example 9 A reaction was carried out in exactly the same manner as in Example 8 except that the reaction temperature was changed to 450 ° C. Table 1 shows the results. Comparative Example 1 The procedure of Example 1 was repeated, except that potassium chloride was not supported after ion exchange.
An L (300) catalyst was prepared. Using the obtained catalyst, a reaction was carried out in exactly the same manner as in Example 1. Table 1 shows the results. Comparative Examples 2 and 3 The firing temperature was 120 ° C. and 550 ° C.
0.5% P in the same manner as in Comparative Example 1 except that
t / KL (120), 0.5% Pt / KL (55
0) A catalyst was obtained. The reaction was carried out in exactly the same manner as in Example 1 except that the obtained catalysts were used. Table 1 shows the results. Comparative Example 4 KCl was prepared in the same manner as in Example 1 except that the amount of potassium chloride was changed so that the molar ratio of potassium chloride to platinum was 1.
A (1) /0.5% Pt / KL (300) catalyst was prepared and reacted. Table 1 shows the results. Comparative Example 5 Potassium chloride and tetraammineplatinum dichloride were dissolved in distilled water, potassium L-type zeolite (TSZ-500, manufactured by Tosoh Corporation) was added, and the solvent was evaporated to dryness. The mixture was calcined at 300 ° C. in an air stream, and further reduced under a hydrogen stream to obtain KCl (4) -0.5% Pt /
A KL (300) catalyst was obtained. The molar ratio of potassium chloride to platinum of this catalyst prepared by the impregnation method was 4, and the catalyst composition was exactly the same as the catalyst of Example 4. The reaction was carried out in exactly the same manner as in Example 1 except that the catalyst obtained by this impregnation method was used. Table 1 shows the results. Comparative Examples 6 and 7 The firing temperature in an air stream was 120 ° C. and 550, respectively.
KCl in the same manner as in Comparative Example 5 except that
(4) -0.5% Pt / KL (120), KCl
(4) A -0.5% Pt / KL (550) catalyst was obtained.
The reaction was carried out in exactly the same manner as in Example 1 except that the obtained catalysts were used. Table 1 shows the results. Comparative Example 8 In Example 4, calcination was carried out at 300 ° C. in an air stream after ion exchange and before impregnation with potassium chloride. The obtained powder was added to an aqueous solution of potassium chloride, and thereafter a catalyst was prepared and reacted exactly in the same manner as in Example 4. Table 1 shows the results. Comparative Example 9 An additional test of Example 1 in JP-A-61-138439 was conducted. That is, to a powder of potassium-type L-type zeolite (TSZ-500, manufactured by Tosoh Corporation), an alumina sol prepared so as to contain 30% alumina was added, and a 1 / 16-inch columnar shape was formed by extrusion molding. A carrier was obtained. To 10 ml of this carrier, 0.165 g of tetraammineplatinum dichloride and 0.149 g of potassium chloride in 17 ml
Was added to a solution dissolved in distilled water. Here, 0.5 ml of a 2N aqueous solution of potassium hydroxide was added. 75 with a shaker
After shaking for minutes, the excess solution was filtered. The catalyst precursor was transferred to a 20 ml eggplant flask and heated at 50 ° C. for 72 hours.
Aged in a closed state. After drying, firing was performed at 110 ° C. for 16 hours, at 200 ° C. for 2 hours, and at 350 ° C. for 3 hours. Finally, reduction was carried out under a stream of hydrogen to obtain a catalyst. The reaction was carried out exactly as in Example 1, except that this catalyst was used. Table 1 shows the results. [Table 1] As is clear from the table, the catalyst supporting Pt and KCl even when calcined at 550 ° C. (Examples 3 and 6)
Showed that the decrease in benzene generation activity was smaller than that of the catalyst not supporting KCl (Comparative Example 3). In addition, it was found that the catalyst in which Pt and KCl were simultaneously supported (Comparative Examples 5, 6, and 7) had significantly reduced benzene generation activity as the firing temperature increased.
As described above, it was found that the benzene-forming activity of the catalyst not according to the present invention was very sensitive to an increase in the calcination temperature. Regarding the difference in the method of supporting Pt and KCl, the catalyst obtained by the impregnation method (Comparative Example 5) was different from the catalyst obtained by the ion exchange method (Example 4) in terms of the reaction conversion and the benzene yield. Was significantly lower, and the isomers methylcyclopentane and isohexane increased. These results indicate that subtle differences in Pt and KCl loading methods can result in significant differences in catalyst performance. As described above, according to the present invention, it is possible to efficiently produce an aromatic compound from a hydrocarbon compound having 6 or more carbon atoms. [0039]

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C07C 5/41 C07C 15/02 C07C 15/04 B01J 29/62 C07B 61/00 300

Claims (1)

(57) [Claim 1] In converting a hydrocarbon compound having 6 or more carbon atoms into an aromatic compound, after carrying out ion exchange of the L-type zeolite with a Group VIII noble metal, the supported amount of the Group VIII noble metal To 2 to 10 times the molar ratio of the alkali metal salt with respect to, and then calcined at 100 ° C to 600 ° C.
A method for producing an aromatic compound, comprising using an L-type zeolite supporting a Group III noble metal and an alkali metal salt as a catalyst.